DE102007055032A1 - Urea water solution tempering system, has control device comprising heating conductor for tempering urea water solution by supplying current to heating conductor, which is connected with positive temperature coefficient element - Google Patents

Abstract

The system has an urea water solution line (10) comprising an internal volume, which is provided for receiving a urea water solution. A control device (20) has a heating conductor (14) for tempering the urea water solution by supplying current to the heating conductor. The heating conductor is electrical conductively connected with a positive temperature coefficient element e.g. positive temperature coefficient thermistor. A temperature measuring device (26) has a temperature measuring sensor i.e. thermo element, which is arranged at a given position inside the internal volume.

Description

Background of the invention

The Invention relates to a system for tempering a urea-water solution, with a fluid conduit having an internal volume suitable for the Inclusion of a urea-water solution is provided.

In certain liquid or gaseous media, it is necessary to temper them when flowing through fluid lines, such as hoses. This is especially true for a urea-water solution after DIN 70070 and CEFIC (European Chemical Industry Council) regulations that are added to the combustion gases of diesel engines, in particular to reduce nitrogen oxide emissions and thus meet the increased requirements of the emissions regulations. For the management of the urea-water solution from a tank for injection into the combustion gases Temperierungsmöglichkeit the fluid line is necessary because the urea-water solution due to the chemical composition has the disadvantage that it flocculates at -11 ° C / freezes. Other negative properties of the urea-water solution are that it is corrosive and creep-capable depending on the temperature.

Out The prior art therefore systems are known in addition to the Lead or intake of a urea-water solution, too for the temperature control of a urea-water solution are formed. Known for the tempering of a Urea-water solution used tempering agents For example, heating conductors are inside or outside one for the flow with a urea-water solution provided fluid line (so-called. HWL line) are arranged. It are therefore basically two different cable variants known, comprising an internal heating, wherein the heating element itself located in the medium to be heated, and an external heating, in which the heating element outside the media-leading Conduit, for example in the form of a tube is located (parallel to the tube or wrapped around the tube).

The Heating conductors of known HWL cables are connected to the 12 V or 24 V on-board voltage commercial vehicles or passenger cars, with only the or switching off the heating above a certain predetermined, minimum outside temperature is controlled.

This has the following disadvantages: The heating element always becomes operated at maximum power (the maximum power will only for a very short time, z. B. needed to thaw the line). The tolerance of the Heizleiterwiderstands is relatively large (approx. +/- 10%), along with a complex design of the heating conductor to the desired temperature range in the corresponding temperature spectrum To achieve success, which requires a high development effort and a high technical complexity brings with it.

Further Known problems arise from voltage fluctuations of the on-board voltages Car (12 V DC) or commercial vehicle (24 V DC). For example Car manufacturers demanded that a reliable Temperature control of the urea-water solution even with voltage fluctuations between 10 V and 16 V can be ensured. This is with the previously known systems hardly possible. There are also overheating (system destruction / fire hazard) at maximum power under consideration of required Thawing times for defrosting a urea-water solution frozen in the line not be ruled out. Furthermore, with the known solutions no performance adjustment for different driving, thawing and environmental situations possible. Other disadvantages of known systems are high energy consumption, the need different resistance wires depending use the required heating power (depending on the cable length) to have and a high development effort in the Heizleiterauslegung.

Further after the heating has been switched on, the heating conductor or resistance wire is switched on always operated with the same power. This has the consequence that the design of the heating conductors made very difficult, as in the case a frozen HWL line this in as short as possible Thawing time (especially at low outside temperatures, which require a high heat output), and because the power consumption at higher temperatures or after thawing as possible should be low to avoid overheating (ie lowest possible power consumption), and because the users or customers want the lowest possible energy consumption (ie as targeted energy use). Overall, considered the design of current heating systems always represents an uncompromising solution. Furthermore it comes because of the above dependencies and the non-linear behavior between resistance and line length to different resistance wires depending from the cable length. This is particularly unfavorable the product design and manufacture, along with high costs, time and development effort for changes and prototypes, high logistical and production costs during production (product safety, likelihood of confusion, dimensional changes, Tool adjustments, etc).

Underlying task

Of the The invention is therefore based on the object, a system for tempering To specify a urea-water solution, with the one opposite known solutions simple and reliable temperature control a received in a HWL line urea-water solution possible, in addition to known solutions is less expensive and uses less energy requires.

invention solution

These Object is according to the invention with an input said system for tempering a urea-water solution solved, the system for tempering the urea-water solution having a control device.

According to the invention So in contrast to known solutions a scheme the heating power or the temperature of the urea-water solution or the fluid line (hereinafter also called HWL line) under Use of a control device, wherein the control device preferably at least a heating element for tempering the urea-water solution by energizing the heating element, wherein in a particular practical training the control device a temperature measuring device and wherein the temperature measuring device at least one Temperature sensor having, at a predetermined Position within the internal volume or in the vicinity of the internal volume is arranged to an actual temperature at the predetermined position and the control device is set up to the actual temperature by energizing the heating element to a predetermined To regulate setpoint temperature. The internal volume can not according to the invention only for the absorption of a urea-water solution but also for guiding or for the flow be provided with a urea-water solution.

The Control device has in this practical training a Temperature measuring device on, via a temperature sensor an actual value of the controlled variable "temperature" in the form of the actual temperature within the internal volume or outside of the internal volume detected, by means of a in the internal volume of the Fluid line temperature sensor arranged the temperature the temperature to be tempered urea-water solution immediately can be recorded or measured.

According to the invention also provided, the temperature sensor outside to arrange the fluid line, the temperature sensor preferably at least partially outside of the fluid line is applied to measure the temperature prevailing at the line. By means of the control device according to the invention In particular, it is possible upon reaching a certain upper temperature, preferably in the form of a predetermined desired temperature the energization of the heating conductor according to the invention turn off and on reaching a certain lower temperature turn back on. Preferably, the temperature sensor on the fluid line and / or on at least one connector or Attachment of the fluid line attached. Preferably takes place here an attachment to a critical point (ie at points or Areas inside the vehicle that are particularly sensitive to a wind exposed, such as unheated connector areas, etc.). According to the invention the temperature sensor necessary in known solutions Temperature sensor for the outside temperature to connect or disconnect the HWL cable or the heating conductor or replace completely. The inventive Control device may preferably in a total or partial control in Vehicle to be integrated, with an existing switching technology partially can be shared, with otherwise preferred simple and inexpensive Components (semiconductor technology) can be used.

Prefers The control device further comprises a controller, preferably in Form of a PID controller, a setpoint generator, one control deviation determining comparator and an output stage for amplification. According to the invention, the urea-water solution forms or the HWL line the controlled system of the invention Control during the heating conductor the actuator and a Heating voltage output by the control device for energizing of the heat conductor forms the manipulated variable.

• • Energieeinsparung durch Regelung der notwendigen Heizleistung,
• • Reduzierung des Risikos von Überhitzungen mit einhergehenden thermischen Schädigungen,
• • Einsatz „leistungsstärkerer" Heizleiter möglich, wodurch ein schnelleres Auftauen einer eingefrorenen HWL-Leitung möglich ist,
• • Nur geringer Zusatzaufwand zur Anpassung an bestehende bzw. bekannte Systeme erforderlich, da bestehende bzw. bekannte Systeme für das Zu- bzw. Abschalten der Heizleistung bzw. des Heizstroms genutzt werden können,
• • „Freie" Positionierung des Temperaturmessfühlers, vorzugsweise in Form eines Thermoelementes an der HWL-Leitung möglich, so dass keine Veränderung an einer bestehenden bzw. bekannten HWL-Leitung notwendig ist und
• • Möglichkeit der Nutzung gleicher Heizleiter für unterschiedliche Längen der HWL-Leitungen und Anforderungen an das Auftauverhalten der jeweils zu temperierenden HWL-Leitung.

Overall, the following advantageous properties are provided by means of this practical development of the system according to the invention for controlling the temperature of a urea-water solution:

• • energy saving by regulation of the necessary heat output,
• • reducing the risk of overheating with associated thermal damage,
• • use of a "more powerful" heating conductor possible, which allows a faster thawing of a frozen HWL line,
• • Only a small additional effort required for adaptation to existing or known systems, since existing or known systems can be used for switching on or off the heating power or the heating current,
• • "Free" positioning of the temperature sensor, preferably in the form of a thermocouple on the HWL line possible, so that no Change to an existing or known HWL line is necessary and
• • Possibility of using the same heating conductors for different lengths of the HWL cables and requirements for the thawing behavior of the HWL cable to be tempered in each case.

• • Kompensationsmöglichkeit der Spannungsschwankungen (quadratischer Einfluss) und der daraus resultierenden Leistungsschwankungen durch die erfindungsgemäße Regelung,
• • Leistungsregelung für unterschiedliche Fahr-, Auftau- und Umgebungssituationen, wie Auftauen, Eisfreihalten usw., realisierbar,
• • Möglichkeit des schaltungstechnischen und programmtechnischen Ausschaltens von Überhitzungen,
• • Bessere Ausnutzung der eingebrachten Energie entsprechend der verschiedenen Fahr-, Auftau- und Umgebungssituationen, einhergehend mit einer geringeren Energieumsetzung und
• • Möglichkeit der Verwendung bzw. Anwendung nur eines Heizleitertypen, da eine Spannungsregelung/Spannungstransformation (bis zu ca. 35 V) möglich ist, einhergehend mit reduzierten Kosten für die Leitungen, die bei entsprechend hohen Stückzahlen kostengünstig erworben werden können.

Further advantageous properties are:

• • Compensation possibility of voltage fluctuations (quadratic influence) and the resulting power fluctuations by the control according to the invention,
• • Performance control for different driving, thawing and environmental situations, such as thawing, freezing, etc., feasible,
• Possibility of switching and program-technical switching off of overheating,
• • Better utilization of the introduced energy according to the various driving, thawing and environmental situations, together with a lower energy conversion and
• • Possibility of using or applying only one type of heating conductor, since voltage regulation / voltage transformation (up to approx. 35 V) is possible, along with reduced costs for the cables, which can be purchased inexpensively with correspondingly high quantities.

at According to an advantageous development, the desired temperature is a constant one Target temperature, wherein in a particularly practical development of Invention, the target temperature is not constant, but one according to a predetermined desired temperature curve variable setpoint temperature is, wherein the control device is adapted to the actual temperature according to the predetermined desired temperature profile to track.

According to the invention by means of this practical training a tracking the temperature according to a reference variable take place in the form of the variable target temperature. Prefers Here is the predetermined target temperature profile the course a thawing curve of the urea-water solution to be tempered adapted to a single typical sections of the thawing curve - such as for example, a flattened area of the thawing curve during a phase transition from solid to liquid - adapted provide controlled temperature control. Preferred according to the invention in the control device at least one, preferably a plurality of Thawing curves in the control device, preferably in specially for this purpose stored storage devices stored to thawing curves to provide for a variety of different applications.

at Another practical development of the invention is the control device further adapted to be measured from a time course of Actual temperatures to detect a temperature jump that is a positive or negative slope whose amount is not smaller as the amount of a given minimum slope. According to the invention so in particular a temperature jump can be detected, which is a predetermined Thawing curve of the urea-water solution can be assigned wherein the temperature jump of the thawing curve is preferably a temperature jump after complete defrosting of the urea-water solution or an ice plug of the urea-water solution. So can with the control device according to the invention when thawing a frozen fluid line (HWL line) preferably The time will be determined from which further heating the fluid line through the heating conductor again with a significant Temperature rise is accompanied. According to the invention it is therefore also possible by means of a temperature sensor, not in the urea-water solution to be tempered is arranged, a suitable control of the temperature of the urea-water solution to realize because a detected temperature jump, for example can be assigned to a temperature that is determined by the given thawing curve the urea-water solution is known. It is crucial in this development, not the actual temperature but the detection of the temperature jump, the case of a complete Defrosting of the ice plug emerges. This is to ensure according to the invention that the temperature sensor is not too close to the heating wire is located in order to prevent a falsification of the temperature profile.

Prefers the temperature sensor is a thermocouple that is in known manner advantageous for accurate temperature measurement can be used anywhere.

at a preferred embodiment of the invention, the temperature measuring device a resistance measuring device for measuring the temperature-dependent Resistance of the heat conductor on to the heat conductor as a temperature sensor to use. Thus, according to the invention on the Use of an additional temperature sensor be waived.

at A practical development of the invention is the fluid line formed in the form of a tube, wherein the temperature sensor preferably at least partially outside of the tube is applied.

In a further practical development of the invention, the tube has a jacket enclosing the insulation, wherein the temperature sensor at least partially in the insulation taken.

at a particularly practical embodiment of the invention is the Temperature sensor in a temperature sensor recording taken at least in sections, the outside of a section the tube is arranged, wherein the temperature sensor recording preferably formed around the tube is collapsible. in this connection is the collapsible training invention preferably created by the temperature sensor recording has two partial receptacles, which are pivotally connected to each other are to take the temperature sensor shot through each other to pivot the two partial shots around the tube fold to be able to.

through the temperature sensor recording of the invention can provide a convenient temperature measurement capability for capture the actual temperature outside or outside of the Fluid line be provided, such that the temperature sensor recording preferably in the form of a practical collapsible "clip" is formed, which "clipped onto the fluid line" can be.

at extends a further practical development of the invention at least one non-recorded portion of the temperature sensor, preferably at least one unattached end portion of the temperature sensor in such a way from one of the two partial recordings of the temperature sensor recording, that he is in the folded state of the temperature sensor recording directed to the other of the two part shots, being the unrecorded portion preferably has a pointed shape having a trained end.

According to the invention the extension is chosen so that the end section during the collapse of the temperature sensor recording to the inventive fluid line to a Outside wall of the fluid line to move and, if appropriate Dimensioning the temperature sensor recording on this impinges or penetrates into this, especially if this with a extruded insulation or sheath made of a polymer is, wherein the not recorded end portion for this preferably has a tip-shaped end. So can in a practical way by simply folding the Temperature sensor recording by one for temperature measurement provided portion of the fluid conduit contact the temperature sensor be provided to the outer wall of the fluid conduit, to measure or detect the temperature of the fluid line.

at an alternative particularly practical training, the Control device at least one PTC element ("Positive Temperature Coefficient "element), unlike the ones described above Further training can in this alternative training the use of a PTC element on a temperature measuring device with Temperature sensor can be omitted.

PTC elements (also PTC resistors, PTC resistors or PTC thermistors called) are known temperature-dependent semiconductor resistors, the at lower temperatures can conduct the electricity better as at high. Your electrical resistance increases with increasing temperature, with PTC elements in particular characterized in that their resistance above a certain temperature increases, with a PTC element further Above a certain voltage, a relatively high self-heating having. This is done in a known manner for measurements and in the control technology. Below this voltage responds the PTC element like a normal resistor and reacts in the Essentially only on foreign warming.

A trained according to the above alternative training Control device preferably includes a simple design at least one PTC element and a current source for energizing the PTC element, wherein the PTC element in this case preferably in environment the internal volume of the fluid conduit or HWL conduit or within of the inner volume is arranged to take advantage of the above Effect of relatively high self-heating ultimately one Heating a recorded in the inner volume of the HWL line urea-water solution to achieve.

As a result The properties of the PTC element here is the heating self-regulating, d. H. at low, local temperatures becomes the PTC element due to its low resistance, high heating power and thus an optionally required strong warming provide. At high temperatures, however, is due to the then present high resistance of the PTC element only a small Heating done. This makes it possible by Arrangement of PTC elements at different locations in the environment of Internal volume or within the inner volume of the HWL cable different Ensure heating intensities.

According to the invention, the energization of the PTC element or the PTC elements preferably via a constant voltage source, such as the 12 V or 24 V on-board voltage of commercial vehicles or motor vehicles, the PTC elements or a PTC element preferably way are thermally insulated by means of a suitable heat-insulating element with respect to the outside environment of the fluid line. Thus, for example, in a preferred development, at least one PTC element can be arranged or mounted on the outside of the fluid line, wherein the fluid line has a jacket of a heat-insulating material, and wherein the PTC element or the PTC elements between the Sheath and the fluid conduit are arranged. As a result of energization of the PTC element or the PTC elements with constant voltage, the thermal properties of the temperature to be tempered depending on the heat-insulating properties of the sheath or the heat-insulating element, the resistance profile of the PTC element as a function of the temperature Urea-water solution, and in particular depending on the external conditions, in particular the outside temperature, at least temporarily set a thermal equilibrium, wherein the urea-water solution has a temperature which may vary depending in particular on the outside temperature.

All in all can therefore be used by appropriate interpretation PTC elements in conjunction with a suitable thermal insulation certain temperatures for the urea-water solution to be tempered be achieved by the external conditions, in particular depend on the outside temperature, with the PTC element or the PTC elements are preferably designed so that they are suitable for a predetermined range of outdoor temperatures sufficient temperature or heating of the urea-water solution.

The Control device can at least in the alternative training a heating conductor, the electrically conductively connected to the PTC element is, in which case the PTC element preferably simply in series in the heating conductor is integrated, and wherein the control device for Energizing the heating conductor and the PTC element a power source having. If the temperature at the PTC element is low, then its resistance is low and a high current flow can through the Heating conductor done. As the temperature increases, however, it grows the resistance of the PTC element, so that thereby the current flow is reduced in the heating element. The PTC element thus provides a Automatic control of the heating output in dependence safe from the temperature conditions.

Brief description of the drawings

following Embodiments of the invention with reference to the attached Drawings explained in more detail. It shows:

1 a schematic cross-sectional sketch of a fluid conduit according to the invention,

2 a schematic sketch of a fluid line according to the invention in conjunction with a control device according to the invention,

3 a schematic sketch of a temperature sensor recording according to the invention,

4 a perspective view of a temperature sensor recording according to the invention in a folded state,

5 a perspective view of a temperature sensor recording according to the invention in an unfolded state,

6 a typical thawing curve of a urea-water solution,

7 an enlarged section of the thawing curve of the 6 comprising the range until the freezing point of the urea-water solution,

8th the time course of a heating voltage comprising a square wave signal for energizing a heating conductor according to the invention.

9 three schematic sketches control devices according to the invention, which have at least one PTC element.

1 shows a schematic cross-sectional sketch of a fluid conduit according to the invention 10 , The fluid line 10 is intended for the absorption of a urea-water solution or for a flow with a urea-water solution (hereinafter HWL line 10 called). The HWL cable 10 includes a tube 12 , one inside the pipe 12 recorded heating conductor 14 , an insulating sheath 16 in the form of a PE foam jacket, and a temperature sensor in the form of a thermocouple (not shown in detail) used to measure the temperature of the tube 12 at least partially abuts the outside of the pipe and in the sheath 16 is included. Alternatively, the heating conductor 14 also on the outside of the pipe 12 be arranged, preferably around the pipe 12 be wound around to provide a tempering of the urea-water solution via an external heating, in which case the thermocouple is preferably at a distance from the heating conductor 14 is arranged in order to avoid a too large measurement error in the temperature measurement or to preclude a falsification of the temperature profile.

By inventively provided Concerning the thermocouple on the outside of the tube 12 the pipe temperature can be detected and measured directly and accurately. Preferably, the thermocouple is located on a straight piece of the tube 12 Alternatively, however, an arrangement in a bend is possible. Optionally, in the area where the thermocouple on the outside of the tube 12 is applied, the insulating sheath 16 be removed.

connecting cables 18 for the thermocouple are at least partially adjacent to the pipe 12 , which is preferably a pipe made of PE material 12 is, on the outside of the pipe 12 along, so preferably at the transition surface between the tube 12 and sheath 16 ,

The connecting cables 18 Alternatively, they may also be completely in corresponding guides, which are inside the sheathing or insulation 16 are formed, be included without the outside of the pipe 12 to abut, preferably such that the connecting lines 18 in the sheath 16 are extruded.

2 shows a schematic diagram of a HWL line according to the invention 10 in conjunction with a control device according to the invention 20 ,

The control device 20 has a temperature measuring device 26 , a regulator 28 , an output stage 30 , Heating conductor 14 and a temperature sensor in the form of a thermocouple (not shown in detail).

The HWL cable 10 has at the illustrated end a connection element 22 on, to which a connector in the form of a tee 24 is connected, at which at right angles to the longitudinal extent of the HWL line 10 extending portion of the tee another connection element 22 is connected, which is provided for connection to a source of urea-water solution or another (not shown here) HWL line. The thermocouple of the control device 20 for measuring the temperature of the HWL cable 10 or the urea-water solution is inside the tee 24 arranged (not shown), wherein sections of connecting cables 18 of the thermocouple to the outside of the HWL line 10 extend. Furthermore, sections or connecting lines also extend 14 otherwise in the HWL line 10 arranged heating element of the control device 20 to outside the HWL line 10 ,

As an alternative to the thermocouple, a temperature sensor in the form of a highly temperature-dependent wire can be provided which extends along the length of the HWL line 10 , preferably along the entire length on the outside of the HWL line 10 extends in order to carry out a continuous, over the length feasible temperature measurement can.

As an alternative to a complete control, it is also possible to provide a control of the heating power, which can take place in such a way that information data relating to the control of an electrical system of a vehicle in which the HWL line is used are used 10 is determined (eg outside temperature, running time of the engine, etc.).

The connecting cables 18 of the thermocouple are to the temperature measuring device 26 the control device according to the invention 20 connected, the temperature measuring device 26 is formed in a known manner to that of the thermocouple via the connecting lines 18 provided measuring signals to provide a measured actual temperature, and this temperature in the form of a temperature signal to a controller 28 supply. The regulator 28 is designed in the form of a PID controller. The controller forms a control deviation in the form of a difference between the measured actual temperature and a predetermined setpoint temperature, processes it according to its mode of operation and generates a signal that is transmitted via an output stage 30 is amplified to provide a manipulated variable in the form of a heating voltage for energizing the actuator in the form of the heating element, in which case sections or connecting lines 14 of the heating conductor are connected to the output stage.

As stated above, the setpoint temperature may be constant or, preferably, a setpoint temperature that changes according to a predetermined setpoint temperature profile, wherein the control device 20 adapted to track the actual temperature according to the predetermined target temperature profile, wherein the predetermined target temperature profile is adapted to the course of a thawing curve of the urea-water solution to be tempered to a single typical sections of the thawing curve - for example, to provide a flattened region of the thawing curve during a phase transition from solid to liquid - adapted controlled temperature control.

3 shows a schematic diagram of a temperature sensor recording according to the invention 32 , The illustrated temperature sensor recording 32 includes two about a movie hinge 34 pivotally interconnected part shots 36 being the movie hinge 34 preferably in the form of one of the two part shots 36 molded elastic material web is formed. Due to the swiveling training is the tempera turmes bulb-receiving 32 around a tubular HWL line 10 formed collapsible, each of the partial shots 36 the temperature sensor recording 32 for receiving the HWL cable 10 to the tube shape of the HWL cable 10 adapted recesses 38 having.

In the upper of the two illustrated recesses 38 two tip-shaped end sections of second thermocouples extend 40 Apart from these end sections, in the upper part intake 36 are included. The end sections serve as measuring points of a thermoelectric voltage and thus a temperature measurement.

By means of the temperature sensor recording according to the invention 32 can be a practical temperature measuring option for detecting the actual temperature outside or outside of the HWL line 10 to be provided.

The end portions extend from the upper part receptacle in this way 36 in that, in particular, in the folded state of the temperature sensor receptacle 32 to the other of the two part recordings 36 are directed towards. According to the invention, the extension is selected so that the end sections during the collapse of the temperature sensor recording 32 to the inventive HWL line 10 preferably on an outer wall of the HWL line 10 impinge and penetrate into this as a result of the pointed shape, especially when the HWL line 10 with an extruded insulation or sheathing 16 made of a polymer material. So can in a practical way by simply folding the temperature sensor recording 32 around a provided for temperature measurement section of the HWL line 10 a contact of the thermocouples 40 to the outer wall of the HWL cable 10 be provided to the temperature of the HWL line 10 to measure or capture.

4 shows a perspective view of another temperature sensor recording according to the invention 10 in a folded state, the two part shots 36 having. Shown is the situation where the temperature sensor recording 32 around a tubular HWL line 10 is folded around. In the temperature sensor recording 32 is for measuring the temperature on the outer wall of the HWL line 10 a thermocouple added (not shown), the connecting cables 18 itself from the temperature sensor recording 32 extend outwardly and the transmission of the measurement signal of the thermocouple to the temperature measuring device 26 the control device according to the invention 20 serve.

5 shows a perspective view of the temperature sensor recording according to the invention 32 in a unfolded state, showing that each of the two partial shots 36 the temperature sensor recording 32 a recess 38 for receiving the HWL cable 10 having. On the left of the two partial shots shown 36 are two locking elements 42 designed to engage in corresponding recesses 44 are formed in the right part recording 36 are formed. Thus, according to the invention, a temperature sensor recording 32 provided, which is in the form of a collapsible "clip", which on the HWL line 10 Can be "clipped".

6 shows by a solid line a typical thawing curve of a urea-water solution. Shown is the temperature of a urea-water solution as a function of the duration of the heating of the urea-water solution, for example, after the operation of the ignition switch, with the first before the actual start of the engine, a heating of a frozen urea-water solution a heating conductor according to the invention 14 is triggered. Shown are typical periods of the thawing curve, comprising a thawing time Ta, a crystallization time Tk at the freezing point at about -11 ° C and a heating time Te. According to the invention, a predetermined target temperature profile can be adapted to the course of the thawing curve in order to provide effective control of the temperature of the urea-water solution during the thawing of a frozen urea-water solution. Dashed is also an idealized course of a thawing curve. 7 shows an enlarged section of the thawing curve of 6 comprising the range until the freezing point of the urea-water solution.

8th shows the time course of a rectangular voltage comprehensive heating voltage for energizing a heating element according to the invention. The heating voltage provided as the manipulated variable of the regulation according to the invention for energizing the heating conductor according to the invention, which represents the actuator, can be designed in the form of a rectangular voltage, comprising heating times t _h with a positive constant voltage and rest periods t _r without energizing the heating conductor at a voltage of zero Volt.

According to the invention, the timing of the square-wave voltage, ie in particular the ratio t _h / t _r can be excited, wherein in particular a reduction of the heating time t _h, a reduction of the heating power can be realized. This is particularly with regard to voltage fluctuations of the on-board voltages of the car (12 V DC) or commercial vehicles (24 V DC) advantageous to, in particular It was demanded by automobile manufacturers to ensure a reliable temperature control of the urea-water solution even with voltage fluctuations between 10 V and 16 V.

in der E die der Harnstoff-Wasser-Lösung während der Heizzeit t_h zugeführte Energie bei der Leistung P darstellt, und in der U die Heizspannung und R der Widerstand des Heizleiters ist, folgendes Verhältnis:

Assuming that the voltage fluctuations include a range that extends from a minimum voltage U _min to a maximum voltage U _max , the respective heating times t _hmin and t _{hmax result} at the minimum voltage U _min and at the maximum voltage U _max taking advantage of the known relationship

in which E represents the energy supplied to the urea-water solution during the heating time t _h at the power P, and in which U is the heating voltage and R is the resistance of the heating conductor, the following relationship:

It follows that relative voltage fluctuations of the on-board voltages have a great influence on the heating times to be realized when using a square wave, which can be compensated by means of inventively provided control by adjusting the ratio t _h / t _r accordingly. For example, in 8th Rectangular signal shown in dashed lines with the voltage U _max of 16 V, a heating time shortened in accordance with the above relationships with respect to the rectangular signal shown by the solid line with the voltage U _min of 10 V.

eine Grundspannung festgelegt werden.Further, according to the invention, upon making an on-line measurement of the resistance R of the heat conductor in the vehicle, according to the relationship

set a basic voltage.

The heating time t _h can also be represented generally as a function of the outside temperature Tau, the resistance R of the heating conductor, the heating voltage U and the thawing time Ta: t H = f (Tau; R; U; Ta).

9 shows three schematic sketches of control devices according to the invention 46 having at least one PTC element.

In the 9 Control device shown above 46 includes a PTC element 48 in series with a heating conductor 14 electrically connected, conductor 50 and a connection device 52 , which is intended for the PTC element 48 , Heating conductor 14 and ladders 50 formed circuit, which is an advantageous simple line construction, to connect to the power supply to a power source or voltage source, wherein the connecting device 52 is preferably designed in the form of a cable set for contacting with a vehicle electrical system of a motor vehicle. joints 54 are designed to provide electrically conductive connections.

The PTC element 48 can at any point on or in the vicinity of a HWL line according to the invention 10 to be ordered. According to the invention, an arrangement of the PTC element 48 and the heating conductor 14 inside the pipe 12 the HWL cable 10 be provided. The PTC element 48 serves as a safety and control element and in particular provides an automatic control of the heating power as a function of the at the PTC element 48 safe temperature. The control device 46 can also be a predetermined plurality of PTC elements connected in series or in series with each other in an electrically conductive manner 48 include. In this case, an effective temperature control or heating of the HWL line 10 or the urea-water solution only if all PTC elements 48 are in a non-critical area, which can be queried according to the invention in addition potential hot areas, which are located for example in the field of exhaust system of a motor vehicle.

The in the middle sketch of the 9 illustrated control device 46 differs from the control device shown in the upper sketch 46 in that no heating conductor is provided, but two conductors 50 via the connection device 52 can be connected to a voltage source, which is preferably a 12 V DC voltage source or a 24 V DC power source of a vehicle electrical system of a motor vehicle, wherein a predetermined plurality of PTC elements 48 arranged in the form of a parallel connection and an electrically conductive connection between the two conductors 50 provide. Again, there is a simple line structure, the PTC elements 48 For example, already in the extrusion production of a HWL line can be introduced into the line.

By means of the illustrated control device 46 can the HWL line 10 be formed selbstregelnd along their entire line length, ie the areas of the HWL line 10 , which are colder, are heated more by the self-regulation than warmer areas. This effect is particularly advantageous if areas of the HWL line 10 are exposed to the wind, z. B. at a line laying in the area of a radiator area of a motor vehicle. This effect can be further enhanced or assisted by using partially different PTC elements with different heating behavior, along with a better use of the available energy. Again, the PTC elements serve 48 as a safety and control element, with other PTC elements z. B. for heating connectors or connecting elements of the HWL line 10 can be provided.

The in the lower sketch of the 9 illustrated control device 46 represents a combination of the control devices described above, and includes a PTC element 48 in series with a heating conductor 14 connected, and two more PTC elements 48 , which are arranged in the form of a parallel connection and an electrically conductive connection between the two conductors 50 provide. The at this control device 46 Parallel connected PTC elements 48 , or further PTC elements, not shown, for example, for heating connectors or connecting elements of the HWL line 10 be provided.

The PTC elements 48 may be PTC elements used by default, but according to the invention can also be assembled for a specific application, such that the corresponding temperature-resistance curve is optimally adapted to the particular application.

10

HWL line

12

pipe

14

heating conductor

16

jacket

18

connecting cable

20

control device

22

connecting element

24

Tee

26

Temperature measuring device

28

regulator

30

output stage

32

Temperature sensor receipt

34

film hinge

36

Receiving sub-

38

recess

40

thermocouple

42

locking element

44

recess

46

control device

48

PTC element

50

ladder

52

connection device

54

junction

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited non-patent literature

• - DIN 70070 [0002]

Claims (19)

System for tempering a urea-water solution, with a fluid line ( 10 ), which has an internal volume, which is provided for receiving a urea-water solution, characterized in that the system for controlling the temperature of the urea-water solution, a control device ( 20 . 46 ) having. System according to claim 1, characterized in that the control device ( 20 . 46 ) at least one heating conductor ( 14 ) for tempering the urea-water solution by energizing the heating conductor ( 14 ) having. System according to claim 1, characterized in that the control device ( 20 . 46 ) at least one PTC element ( 48 ) having. System according to claim 3, characterized in that the control device ( 20 . 46 ) at least one heating conductor ( 14 ) electrically conductively connected to the PTC element ( 48 ) connected is. System according to claim 2, characterized in that the control device ( 20 . 46 ) a temperature measuring device ( 26 ), wherein the temperature measuring device ( 26 ) at least one temperature sensor ( 40 ) disposed at a predetermined position within the interior volume or in the vicinity of the interior volume to measure an actual temperature at the predetermined position, and wherein the controller (16) 20 ) is adapted to the actual temperature by energizing the heating conductor ( 14 ) to regulate to a predetermined target temperature. System according to claim 5, characterized in that the target temperature is a constant target temperature. System according to claim 5, characterized in that the setpoint temperature is a setpoint temperature curve variable according to a predetermined target temperature, wherein the control device ( 20 . 46 ) is adapted to track the actual temperature according to the predetermined target temperature profile. System according to claim 7, characterized in that the predetermined target temperature course the course of a thawing curve adapted to be tempered urea-water solution is. System according to one of claims 5 to 8, characterized in that the control device ( 20 . 46 ) is further adapted to detect from a time course of measured actual temperatures a temperature jump, which has a positive or negative slope whose amount is not smaller than the amount of a predetermined minimum slope. System according to one of claims 5 to 9, characterized in that the temperature sensor is a thermocouple ( 40 ). System according to one of claims 5 to 10, characterized in that the temperature measuring device ( 26 ) a resistance measuring device for measuring the temperature-dependent resistance of the heating conductor ( 14 ) to the heating conductor ( 14 ) to be used as temperature sensor. System according to one of claims 5 to 11, characterized in that the fluid line ( 10 ) in the form of a tube ( 12 ) is trained. System according to claim 12, characterized in that the temperature sensor at least partially outside of the tube ( 12 ) is present. System according to claim 12 or 13, characterized in that the pipe ( 12 ) one the pipe ( 12 ) jacketing insulation ( 16 ), wherein the temperature sensor ( 40 ) at least in sections in the insulation ( 16 ) is recorded. System according to one of claims 12 to 14, characterized in that the temperature sensor ( 40 ) in a temperature sensor recording ( 32 ) is received at least in sections, the outside of a portion of the tube ( 12 ) is arranged. System according to claim 15, characterized in that the temperature sensor recording ( 32 ) around the pipe ( 12 ) is formed folded around around. System according to claim 16, characterized in that the temperature sensor recording ( 32 ) two partial recordings ( 36 ), which are pivotally connected to each other. System according to claim 17, characterized in that at least one non-recorded portion of the temperature sensor ( 40 ), preferably at least one non-recorded end portion of the temperature sensor ( 40 ), so from one of the two sub-images ( 36 ) extends in the folded state of the temperature sensor recording ( 32 ) to the other of the two partial recordings ( 36 ) is directed. System according to claim 18, characterized draws, that the non-recorded portion has a tip-shaped end.